Exergy and Exergy Cost Analysis of production systems incorporating renewable energy sources

Exergy is a thermodynamic quantity capable of measuring the conversion of material and energy flows into comparable terms based on the capacity of such flows to generate mechanical work as a useful effect and identifying and quantifying the thermodynamic inefficiencies of a generic process by means of the exergy destruction term. Because of its properties, an exergy is a convenient tool for the calculation of the global resource consumption of both natural and engineering processes. Therefore, there are different exergy-based approaches. Every exergy-based approach has its advantages and its drawbacks. It even has its own spatial and temporal domain [1]. There are different exergy-based approaches that have been reviewed which are EMergy, Extended Exergy, Cumulative Exergy Consumption, Exergetic life cycle assessment, and Thermoeconomics. Reviewing different exergy approaches, especially the approaches that introduce the externalities like Labour, Capital, and environmental cost with their equivalent exergy values will help to develop an approach that avoids the drawbacks and take advantage of other approaches. Exergy-based account methodologies do not account for the ecological processes and products. This is something savior if sustainability is the aim and the goal. The indirect cost of resource consumption must be counted. The exergy cost of mineral resources which are not renewable is not their chemical exergy embodied in them only but also the cost of exergy that has been to be spent to reconcentrate these resources to be available for the upcoming generations [2]. As it is a matter of sustainability, considering the indirect exergy cost is very important. Each exergy-based methodology has its own spatial and temporal boundary. Some of them account only for the exergy consumed during the operation phase like the basic exergy analysis and some of them extend its spatial boundary to include the ecological cumulative exergy cost of a specific product [3]. The ecological cumulative exergy consumption ECEC approach has been introduced by Szarjut. Another approach extends its spatial boundary including the economy of the region or a country where the analysis takes place. This allows some other externalities like money and labor to be accounted for in form of exergy. This approach is the extended exergy analysis EEA. This thesis presents a conceptual development of sustainability evaluation, through an exergy-based Indicator, by using the new concept of the Thermoeconomic Environment (TEE). The exergy-based accounting methods here considered as a background are the Extended Exergy Accounting (EEA), which can be used to quantify the exergy cost of externalities like labor, monetary inputs, and pollutants, and the Cumulative Exergy Consumption (CExC), which can be used to quantify the consumption of primary resources “embodied” in a final product or service. Also, the new concept of bioresource stock replacement cost is presented, highlighting how the framework of the TEE offers an option for evaluating the exergy cost of products of biological systems. The sustainability indicator is defined based on the exergy cost of all resources directly and indirectly consumed by the system, the equivalent exergy cost of all externalities implied in the production process and, the exergy cost of the final product.

Exergy is a thermodynamic quantity capable of measuring the conversion of material and energy flows into comparable terms based on the capacity of such flows to generate mechanical work as a useful effect and identifying and quantifying the thermodynamic inefficiencies of a generic process by means of the exergy destruction term. Because of its properties, an exergy is a convenient tool for the calculation of the global resource consumption of both natural and engineering processes. Therefore, there are different exergy-based approaches. Every exergy-based approach has its advantages and its drawbacks. It even has its own spatial and temporal domain [1]. There are different exergy-based approaches that have been reviewed which are EMergy, Extended Exergy, Cumulative Exergy Consumption, Exergetic life cycle assessment, and Thermoeconomics. Reviewing different exergy approaches, especially the approaches that introduce the externalities like Labour, Capital, and environmental cost with their equivalent exergy values will help to develop an approach that avoids the drawbacks and take advantage of other approaches. Exergy-based account methodologies do not account for the ecological processes and products. This is something savior if sustainability is the aim and the goal. The indirect cost of resource consumption must be counted. The exergy cost of mineral resources which are not renewable is not their chemical exergy embodied in them only but also the cost of exergy that has been to be spent to reconcentrate these resources to be available for the upcoming generations [2]. As it is a matter of sustainability, considering the indirect exergy cost is very important. Each exergy-based methodology has its own spatial and temporal boundary. Some of them account only for the exergy consumed during the operation phase like the basic exergy analysis and some of them extend its spatial boundary to include the ecological cumulative exergy cost of a specific product [3]. The ecological cumulative exergy consumption ECEC approach has been introduced by Szarjut. Another approach extends its spatial boundary including the economy of the region or a country where the analysis takes place. This allows some other externalities like money and labor to be accounted in form of exergy. This approach is the extended exergy analysis EEA. This thesis presents a conceptual development of sustainability evaluation, through an exergy-based Indicator, by using the new concept of the Thermoeconomic Environment (TEE). The exergy-based accounting methods here considered as a background are the Extended Exergy Accounting (EEA), which can be used to quantify the exergy cost of externalities like labor, monetary inputs, and pollutants, and the Cumulative Exergy Consumption (CExC), which can be used to quantify the consumption of primary resources “embodied” in a final product or service. Also, the new concept of bioresource stock replacement cost is presented, highlighting how the framework of the TEE offers an option for evaluating the exergy cost of products of biological systems. The sustainability indicator is defined based on the exergy cost of all resources directly and indirectly consumed by the system, the equivalent exergy cost of all externalities implied in the production process and, the exergy cost of the final product.